Last month, my youngest son, Lindell, began to read. It was simple words at first; he noticed the “Open” sign in a window at the barber shop and the word “Sale” at the grocery store. Soon, however, he was asking for help with bigger words—”restaurant,” “appointment,” “excludes,” “BOGO” (“BOGO?”)—that he saw around him.

Before I could grasp what was happening, he called me into his bedroom and said, “I’ll read the bedtime story to you tonight.”

This means that I have no more babies, and my feelings are mixed.

On the one hand, it is fun to watch Lindell figure out the written world around him. His older brothers and I love to listen to him sound out words, like when he saw the word “office” and pronounced it “off-ice” at first.

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“Try again,” Ford, 12, said.

“Of-ice?” Lindell said. “Off-ise? No. Wait! Office! It’s office!”

And on a recent trip to The Briar Patch, our favorite local bookstore, instead of rolling on the floor and making noise (his usual method of operation), Lindell ran to “his section” to find a book. He was so excited that the Mercy Watson series — the same one the school librarian reads to his class — is on “his level.”

“You mean I can read Mercy Watson by myself?” he asked, his eyes wide and sparkling.

But written words are in many ways the final gatekeeper of innocence. They are the vehicle for grown-up conversation: “Will you please put them to B-E-D E-A-R-L-Y so that we can eat more D-E-S-S-E-R-T?” They are what allow parents to change the rules of CandyLand without any protests: “The rules say that if I draw a purple card twice, the game is over and it’s time for bed.”

They are what keep young children like Lindell from accidentally reading the front page of the newspaper and learning what happened at Sandy Hook Elementary.

In the “Disappearance of Childhood,” Neil Postman argues that, in fact, the invention of the printed word is what created the concept of “childhood” to begin with. Words came to hold adult secrets that couldn’t be unlocked until reading was mastered. Until then, children live in a blissful state, unburdened by things meant (ie: written) only for adults.

I saw this with my oldest son, Ford, 12, who also started reading in kindergarten. Looking back, that’s when he officially stopped being my little guy — the one who called me into his room for “one last story” and held my hand as we walked through a store, pointing with his other hand at things we passed (“What’s that Mommy?”). It was the tipping point to him heading down the path to independence. Today, he shuts himself in his room to read. He no longer asks for help with big words. He has his own email account.

Lindell is just beginning this process, and I am happy and sentimental.

There have been some truly funny moments, like when Lindell reads magazine headlines in the grocery store checkout line. Unlike older, wiser, well-read Ford, Lindell doesn’t yet know that reading these out loud might be funny and inappropriate: “Look, Mom, that says, ‘Saving myself for marriage,’ and that says, ‘pregnant by another man.'”

When we pass by the greeting card section, a real danger zone for mothers with emerging readers, Lindell reads everything that he can: “I wanted to get you a woman for your birthday….Pull my finger…This hot girl in a bikini has one wish for you…”

Many times, I have to intercept and tell him that he can’t open the cards and read the inside. Unfortunately (fortunately?), this make him even more eager to learn new words.

But last week, when I overheard Owen coaching Lindell on the correct pronunciation of the word “other,” things suddenly became very real. And kind of sad.

Lindell was reading aloud and said, “udder.” Owen said, “It’s time for you to start saying ‘other,’ not ‘udder.”

“Udder?” Lindell said.

“No, other.”

“Udder.”

“Say it with me, oth-her.”

“Ud-der.”

“No, other. Oth-her.”

“Udder.”

“Geez, Lindell, you sound like a baby.”

I went into the room where both boys were reading in their beds. Owen nearly fills his up, and his bookshelf is stocked with thick, tattered books like Harry Potter and H.I.V.E.

Lindell looks like a little peanut in his big, twin bed. His bookshelf is filled with Mercy Watson and Dr. Seuss books that haven’t had enough time to be tattered.

I kissed each boy on the top of his head as I turned out the reading lights. But when I got to Owen, I whispered in his ear, “Let’s let him say ‘udder’ just a little bit longer. There is plenty of time for ‘other.'”